Composite end connection for steel joists

ABSTRACT

A joist end connection providing composite action between a supporting beam and a concrete slab when the bearing end of the joist is encased in the concrete slab whereby the encased joist end is employed as a shear connector. This is accomplished by employing metal formwork and anchoring means for keying the supporting beam to the concrete at the bearing end of the joist.

[ 51 Aug. 15, 1972 United States Patent McManus [54] COMPOSITE ENDCONNECTION FOR 10/1931 Sealey.........................52/421 3,147,5719/1964 Welch........................

STEEL JOISTS [72] Inventor:

Ira J. McManus, 39 Lincoln Ave., 2/ 35 Fl h p k NJ. 0794 3,392,499McManus....................52/333 Oct. 8, 1970 Primary Examiner-Henry C.Sutherland Attorney-James J Cannon [22] Filed:

[21] Appl. No.: 79,022

[57] ABSTRACT A joist end connection providing composite action betweena supporting beam and a concrete slab when the bearing end of the joistis encased in the concrete [52] US. 52/336 [51] Int. 1/16, 1504b 5/29[58]. Field of Search........................52/334-336, 340,

slab whereby the encased joist end is employed as a [56] ReferencesC'ted shear connector. This is accomplished by employing UNlTED STATESPATENTS I metal formwork and anchoring means for heying the supportingbeam to the concrete at the bearing end of 1,863,258 6/1932 Tashlan..............;.......52/336 the joist 1,734,358 11/1929Yeager........ ....52/334 910,757 1/ 1909 Wilson 52/336 8 Claims, 8Drawing Figures PATENTEDaus 1 5 I972 SHEET 2 BF 3 WI" "I'm CONNECTIONFOR STEEL JOISTS CROSS-REFERENCE TO RELATED APPLICATIONS In my U.S. Pat.No. 3,392,499, issued July I6, 1968,

COMPOSITE END and co-pending US. Pat. applications, Ser. No.

751,930, filed Aug. 12, 1968, now US. Pat. No.

3,527,007 and Ser. No. 10,399, filed Feb. 11, 1970,

now US. Pat. No. 3,624,980 there are disclosed various novelimprovements relating to end connections between open-web steel joistsand steel beams or girders supporting them such that there is obtainedcomposite action between the supporting beam or girder and a concreteslab poured over the joists so as to completely encase the bearing endsof the joists. The present invention is directed toward improvements'over the steel joist end connections disclosed therein.

SUMMARY OF THE INVENTION The present invention relates to a novel andimproved end connection for steel joists where at the bearing ends ofthe joists there there is provided in one embodiment a unitary metal panincluding a flat bottom surface and outwardly sloping sides extendingupward above the top chord of the joist to provide support at thebearing ends of the joist for the concrete to DESCRIPTION OF THEPREFERRED EMBODIMENTS Having reference to the accompanying drawingswherein like reference numerals designate similar parts, there is shownin-FIGS. 1 through 4 a first embodiment of the invention comprisingstandard openweb steel joists 10, each of which comprises top pairs ofopposed angle irons l2 and 14 secured by conventional means such weldingalong their 'apice's at upper extremity of a zig-zag shaped bar web 16to form the top chord of each of the joists, and a bottom pan of opposedangle irons l8 and 20 (only one pair being partially shown) similarlysecured at the bottom extremity of the bar web 16 to form the bottomchord of each joist 10. At the bearing end of the top chord of each bepoured thereover, and anchoring means secured at one end to the joistsand extending upward into keying relationship with the main body of theconcrete. Accordingly, it is a primary object of the present inventionto provide a novel and improved end bearing connection for steel joistswhereby there is obtained composite action between the supporting steelbeam or girder and the concrete encasing the joist end.

Another object of the present invention is to provide a novel andimproved end connection for open-ended steel joists wherein at thebearing end of the joists there is provided smooth-surfaced metal panmeansfor receiving concrete to be poured into encasing relationship withthe joists.

'A further object of the present invention is to provide a novel andimproved end bearing connection for steel joists wherein the desiredcomposite action between the supporting member and encasing concrete iseffected by means of a unitary metal form or separate opposed metal.forms disposed at the bearing ends and anchoring means operably keyingthe supporting member to the concrete through the steel joists.

Various other objects, features and advantages of the present inventionwill become apparent from the following detailed description of theinvention when read in connection with accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a perspective viewof a joist end connection constructed and arranged according to the tionencased in a concrete slab;

FIG. 4 is a cross-sectional view taken substantially along the line 4-4in FIG. 3; v

joist there is provided a pair of opposed seat angles 22 and 24, whicheither may be separate from or integrally formed with the top chord ofthe joist. These seat angles 22, 24 extend below the top chord for apredetermined distance whereupon the angles are formed with laterallyoutward extending flanges 26, 28, respectively, to form a substantiallyU-shaped member or channel. These seat angles,which are encased in aconcrete v slab 30 (see FIG. 3), as hereinafter described in detail,

seat upon a supporting composite beam or girder 32 and are securedthereto by suitable means, such as welding, to provide the necessaryshearing strength in the direction of the longitudinal axis of thesupporting beam 32 (which axis is perpendicular to that of the joists)by rigidly connecting the concrete slab 30 to the beam or girder 32 TheU-shaped construction of the joist end seat angles enhance encasement ofthe concrete to the support beam through the joist end connection.

At each joist bearing end there is provided anchoring means 34, whichmay take the form of a headed stud or bolt 34' or a hooked rod 34", andwhich is snugly fitted between and secured to the opposed angle irons12, 14

and the seat angles 22, 24 as by welding designated 58 or the like asshown in FIG. 4. The anchors 34, as best shown in FIG. 3, extend upwardabove the top chord of each joist into keying relation with the mainportion of the concrete slab 30 poured over, such that the anchor issolidly embedded therein whereby the slab securely is interconnectedwith the supporting beam or girder 32 through the joist end connection.

Corrugated sheet metal fonn plates 36, as shown in FIGS. 1, 2 and 3, areplaced along the top chords of adjacent parallel joists between the endsthereof to form a bottom support for the concrete slab 30 to be pouredover. These forms 36 extend between the seat angles 22, 24 provided ateach joist end (see FIG. 3). To prevent any leakage of the concrete whenpoured along 1 the sides of the joist ends there is provided over eachjoist end a substantially U-shaped notched metal closure plate 38. Eachplate 38 comprises a top surface or bright portion 40 and a pair ofsimilar notched vertical sides or legs 42, the notches being formed asat 44 so that a forward portion 46 of each side 42 may be bent inwardlytoward the corresponding vertical side of the joist end to prevent anyleakage of the concrete beyond the desired area at the joist end, whichcould detract from the desired connection between the beam or girder 32and the concrete 30.

On top at each joist end there is provided a continuous support rod 48,which rod extends continuously between adjacent parallel joists and issecurely connected thereto by means of welding. These rods in thepreferred embodiment of FIGS. 1 to 4 support the ends of a unitary orsingle metal pan 50 situated at each joist end connection. The pan 50comprises a flat bottom 52, upwardly outward sloping sides 54 andmarginal downward sloping sides 56, and is of sufiicient width to fitsnugly between adjacent parallel closure plates to prevent leakage ofconcrete. The metal pan 50 is supported at its ends by the support rod48 disposed directly below the bend formed between 54 and 56. The bottom52 is supported by the top flange of the supporting beam. Theextremities of the corrugated metal formwork 36 are supported by themarginal ends 56 of the pan 50.

As described heretofore, in order to obtain the desired composite actionbetween the concrete slab 30 and supporting beam 32 there is provided ananchor 34 in the form of a headed stud or bolt 34 or hooked rod 34"secured between the back-to-back top chord angles 12, 14 and the seatangles 22, 24, respectively, forming the joist bearing end and securedthereto by welding shown as 58 to obtain the necessary keying of theconcrete to the joist end. Other alternates for obtaining the desiredkeying action are shown in FIGS. and 6, where there is illustrated acontinuous rod 60 including top keying members 62 (see FIG. 6) andbottom support members 64 interconnected by sloping sides 66. The rods60 are welded as at 68 in the field, preferably to the top chords of thejoists. The keying members 62 of each rod 60 are sufficiently spacedvertically above the top chords within the main body of the concrete 30,that is, above the center line of the concrete slab 30, to effect thedesired composite action.

As illustrated in FIGS. 7 and 8, in lieu of the previously describedmetal pan 50 and metal closure plates 38, there is provided pan ofseparate notched metal plates 64 which are designed to fit snuglybetween the vertical sides of the joist bearing ends to prevent anyconcrete leakage. These notched plates 64 each comprise a flat bottomsurface 66 secured by welding to the top flange of the supporting beamor girder 32, a side wall 68 which slopes upward away from thelongitudinal center line of the supporting beam 32 and a central bentmarginal member 70 having a terminal downward sloping side 72. Thecontinuous rod 48 supports the end of the plates 64 by engaging thesides 70 and 72 at their bend. A pair of notched downwardly bent comermembers 74 are disposed on either side of the central member 70 so as tobe located below the horizontal laterally extending flanges 76 of thetop chord angles 12 and 14 (only 14 being shown in FIG.

7). To place these metal plates 64 properly in position the plate isslid horizontally toward the supporting beam or girder between thelateral flanges 76 of the joist top chords past the support rod 48. Thecentral bent member then is raised into its supported position by therod 48 (see FIG. 8) with the notched corners 74 being disposed below theflanges 76 of the top chord (see FIG. 7). However, for convenience thesecomers may be removed completely before installation of the plates 64.

While there have been disclosed herein various forms of the presentinvention, it is to be understood that such forms are preferred only andshould not be construed as limited of this invention in any sense. Thus,while there has been disclosed steel joists comprising angle members,the novel features of this invention may be employed with other typesand-configurations of joist ends. Accordingly, reference should be madeto the following appended claims to determine the full extent of thescope of protection afforded by the present invention.

Having thus set forth the nature of the invention, what is claimedherein is:

1. In a steel joist construction and end connection therefor, thecombination comprising, first and second pairs of parallel steel joists,anchor means extending upwardly from the ends of each pair of steeljoists, each of said joists having a top chord, a bottom chord and meansfor securing said top and bottom chords in vertically spaced relation,said top chord having a seating angle provided at its ends extendingbelow said top chord and being supported by a beam running in adirection substantially perpendicular to the direction of said steeljoists, closure form means of inverted U- shape seated on the top chordsof each joist adjacent the ends thereof, each closure form means havinga bight portion seated on the top of each top chord and pairs of legsextending from the bight portion to the upper surface of said beambetween said joist seat angles, a sealing plate form means disposedbetween the parallel joists of each pair, each sealing plate form meansincluding flat bottom means supported by said beam and oppositelyoutward sloping sides supported at its ends by rods extending betweenparallel ones of said steel joists, said sealing plate having its edgesin contact with the legs of said closure form means, whereby when aconcrete slab is poured over said concrete form means in the vicinity ofsaid steel joist end connection into encasing relation with said endconnection there is obtained composite action therebetween.

2. A steel joist end connection according to claim 1 wherein said anchormeans extends upwardly from the end of said steel joists above said topchords to enhance the interlocking action between the concrete slab andthe joist end connection.

3. A steel joist end connection according to claim 2 wherein said anchormeans comprises a continuous member extending between parallel ones ofsaid steel joists and having lower portions secured to the top of saidsteel joists and upper portions adapted to be embedded within saidconcrete slab.

4. A steel joist end connection according to claim 3 wherein the legs ofsaid closure means have a portion thereof nearest said steel joist endbent inwardly into contact with the vertical sides of said steel joists.

5. A steel joist end connection according to claim 1 wherein said plateform means comprises a unitary pan comprising a continuous bottom andsides for providing a receptacle for the concrete slab in the vicinityof said end connection.

6. A steel joist end connection according to claim 5 wherein said sideseach slope outwardly and have bent outer portions to facilitatesupporting said second concrete form means by said supporting rods.

7. A steel joist end connection according to claim 1

1. In a steel joist construction and end connection therefor, thecombination comprising, first and second pairs of parallel steel joists,anchor means extending upwardly from the ends of each pair of steeljoists, each of said joists having a top chord, a bottom chord and meansfor securiNg said top and bottom chords in vertically spaced relation,said top chord having a seating angle provided at its ends extendingbelow said top chord and being supported by a beam running in adirection substantially perpendicular to the direction of said steeljoists, closure form means of inverted U-shape seated on the top chordsof each joist adjacent the ends thereof, each closure form means havinga bight portion seated on the top of each top chord and pairs of legsextending from the bight portion to the upper surface of said beambetween said joist seat angles, a sealing plate form means disposedbetween the parallel joists of each pair, each sealing plate form meansincluding flat bottom means supported by said beam and oppositelyoutward sloping sides supported at its ends by rods extending betweenparallel ones of said steel joists, said sealing plate having its edgesin contact with the legs of said closure form means, whereby when aconcrete slab is poured over said concrete form means in the vicinity ofsaid steel joist end connection into encasing relation with said endconnection there is obtained composite action therebetween.
 2. A steeljoist end connection according to claim 1 wherein said anchor meansextends upwardly from the end of said steel joists above said top chordsto enhance the interlocking action between the concrete slab and thejoist end connection.
 3. A steel joist end connection according to claim2 wherein said anchor means comprises a continuous member extendingbetween parallel ones of said steel joists and having lower portionssecured to the top of said steel joists and upper portions adapted to beembedded within said concrete slab.
 4. A steel joist end connectionaccording to claim 3 wherein the legs of said closure means have aportion thereof nearest said steel joist end bent inwardly into contactwith the vertical sides of said steel joists.
 5. A steel joist endconnection according to claim 1 wherein said plate form means comprisesa unitary pan comprising a continuous bottom and sides for providing areceptacle for the concrete slab in the vicinity of said end connection.6. A steel joist end connection according to claim 5 wherein said sideseach slope outwardly and have bent outer portions to facilitatesupporting said second concrete form means by said supporting rods.
 7. Asteel joist end connection according to claim 1 wherein said sealingplate form means comprises a pair of opposed separate metal membersextending between adjacent one of said parallel pairs of steel joists.8. A steel joist end connection according to claim 7 wherein said metalmembers each have notched marginal corner portions underlying thesupporting rod and a centrally disposed bent member which overlies andis supported by said supporting rod.